Many wireless devices radiate radio frequency energy (and/or receive radiated radio frequency energy) that carries an informational payload. In many cases, a given antenna will be carefully selected and matched to work effectively with a given transmitter/receiver. In general, such an approach provides satisfactory results in a number of varied applications.
Some wireless communications techniques are better facilitated with multiple antennas. Some known architectures provide for a dual mode antenna wherein only one of the two modes can be utilized at any given time. Other multiple antenna applications exist as well. For example, many diversity approaches use two or more antennas. As another example, applications such as Multiple Input Multiple Output (MIMO) and Bell Labs Layered Space Time (BLAST) are typically effected with at least two antennas per transmitter/receiver.
While such applications provide numerous benefits, the attendant need for multiple antennas sometimes militates against use of such techniques in certain situations. For example, applications that are particularly sensitive to cost limitations and/or space/form-factor limitations are not ideal candidates for a multiple antenna architecture. Hand-held subscriber units, for example, tend to be relatively small with cost limitations often strongly influencing configuration choices.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.